The term "steering knuckle" as used herein and is generally understood in the art refers to a unitary mechanical device which is configured to fit into the wheel base of the front wheels of a motor vehicle, and this device mechanically interconnects and couples the vehicle steering tie rods and ball joints to the wheel base assembly. This steering knuckle device includes, among other things, a spindle which is adapted to be received along the rotational axis of the front wheels of a vehicle, and a tie rod arm which is approximately orthogonal to the spindle and has a bore at one end thereof for connecting to a tie rod. This device further includes a centrally located rotational pivot for receiving ball joint arms which operate to provide a central axis of rotation for the device, and it further includes a brake caliper mounting flange positioned on the opposite side of the device from the tie rod arm.
Thus, as is generally well known in the art, the movement of the tie rod of a motor vehicle by an operator turning the steering wheel of the vehicle will produce a corresponding force at the end of the tie rod arm which causes the steering knuckle to rotate about its central axis of rotation. This motion causes the spindle to rotate the wheel of the vehicle in either a clockwise or a counterclockwise direction depending upon whether the tie rod is pushing against or pulling on the ends of the tie rod arms. This operation has been described in detail in many prior art references, including, for example, U.S. Pat. No. 4,600,205 issued to Stewart et al and incorporated herein by reference.
Steering knuckles of the known prior art have their central rotational pivot located in or near the plane in which the tie rod arm is located. Thus, the torque applied to the end of the tie rod arm by the lateral movement of the vehicle tie rods is equal to the effective length of the tie rod arm multiplied by the lateral force applied thereto by the tie rod movement. Thus, the arcuate distance of travel in radians of the end of the spindle and defining the turning angle of the wheel into which the spindle is mounted is linearly proportional to the arcuate distance in radians traveled by the end of the tie rod arm.
In order to increase the arcuate distance of travel of the spindle in response to a fixed tie rod travel distance and thus increase the turning angle of the steering knuckle as may be desired for certain types of vehicular turning applications, this could be achieved simply by reducing the length of the tie rod arm. However, the problem with this approach alone is that it significantly increases the torque required to turn the wheel through a given turning angle and it also reduces the overall steering stability of the vehicle.